This invention relates to a magnetic record member for use in magnetic recording devices such as a magnetic disc and a magnetic drum and a process for manufacturing the same. In general, recording and reproducing systems for the magnetic recording device consisting of heads for recording and reproducing (referred to simply as "head" hereinafter) and magnetic record members may be classified into two types. In one system, upon initiation of operation, a head is brought into contact with the surface of a magnetic record member and then, the record member is rotated at a given speed in a manner to provide a spacing between the head and the magnetic record member surface, thereby enabling the recording and reproducing operations. According to this system, upon completion of operation, rotation of the record member is stopped in a state where the head and the record member are maintained in frictional contact with each other as in the case with the starting of operation.
In another system, after the magnetic record member is rotated at a given speed beforehand, the head is suddenly urged against the record member surface to give a spacing due to an air layer created between the head and the record member so as to perform the recording and reproducing operations. In this manner, according to the first system, the head is maintained in frictional contact with the magnetic record member surface both upon initiation and completion of the operation. On the other hand, in the second system, the head is maintained in frictional contact with the magnetic record member surface when it is urged against the magnetic record member surface. Such frictional contact tends to wear both the head and the record member and to harm a magnetic metal thin film medium formed on the record member. Also, in such a frictional contact state, a slight change of the head-attitude makes a load imposed on the head non-uniform so that the head and the record member are damaged.
In addition, the frictional force exerted by the frictional contact of the head with the magnetic record member surface causes a large torque to a motor, particularly in case where a plurality of heads are used, which imposes an undesirable load on the motor adapted to rotate the record member
Furthermore, in case where the head unexpectedly, and usually abruptly, contacts the record member surface, both the head and record member are damaged due to a large frictional force present between the head and the record member.
For the purpose of protecting the head and magnetic record member from the aforesaid frictional force caused between the head and the record member, it is required to provide a protective film on the surface of the magnetic record member. The protective film in this respect should minimize the frictional force exerted between the head and the magnetic record member or, in other words, the protective film must provide as low a coefficient of friction as is practical.
In this connection, the provision of a lubricant layer on the surface of the magnetic record member is one method to minimize the frictional force.
U.S. Pat. No. 3,466,156 discloses the provision of such a lubricant layer of natural or synthetic wax on the surface of the magnetic record member. However, the lubricant layer of wax fails to give a sufficient adhesion to an underlayer so that the wax layer is peeled from the underlayer due to a plurality of cycles of repeated frictional contacts of the head against the magnetic record member, thus failing to meet the intended practicability. For this reason, the aforesaid lubricant layer must adhere to the underlayer in a satisfactory manner. Insufficient adhesion of the lubricant layer to its underlayer results in the peeling of the lubricant layer from the underlayer due to a frictional force caused between the head and the magnetic record member and/or results in the accumulation of lubricant between the head and the record member or around the head due to capillarity. As a result, detrimental influences are imposed on the flying stability of the head during the recording and reproducing operations.
The interposition of a nonpolar molecular layer invulnerable to adsorption or adhesion to the head surface along an interface between the head and the magnetic record member contributes to the minimization of a frictional force exerted between said lubricant layer and the head. In other words, it is preferable that the lubricant layer is oriented so as to create a portion combining the magnetic record member and a nonpolar portion reluctantly adhering or absorbing to the head surface.